R2#sh run | b key
key chain Prob4
 key 1
  key-string cisco
!
interface Serial1/2
 ip address 180.40.7.2 255.255.255.224
 ip rip authentication mode md5
 ip rip authentication key-chain Prob4
 clock rate 64000
!


R3#sh run | b key
key chain Prob4
 key 1
  key-string cisco
!
interface Serial1/2
 ip address 180.40.7.3 255.255.255.224
 ip rip authentication mode md5
 ip rip authentication key-chain Prob4
!